"Silicone oil" is also available as "toner fuser oil" for photocopiers, and (believe it or not) Spa ani-foam agent (although I suspect the latter is a pretty dilute suspension in (mostly) water.) There's actually a wide variety of viscosities available (depending on the molecular weight of the POLYmer; it might be worth experimenting... (http://www.chemistrystore.com/ has three different viscosities, as long as you buy a gallon at a time!)

In the most recent datasheet (Atmel-42735-8-bit-AVR-Microcontroller-ATmega328-328P_Datasheet.pdf), the terms used are actually "Low Pass Filter" (section 5.2.7) and "LC Network" (section 28.6.2) The schematic 28-9 shows a 10uH inductor.(It's just a nit, of course. Any circuit built on a breadboard is unlikely to need (or benefit from) this degree of attention paid to the Vcca)

A couple of comments:1) re Ferrite bead on Vcca: AVR042 actually recommends the ferrite bead between the system power plane and digital Vcc, and the m328 datasheet recommends an actual inductor between Vcc and Vcca (as well as a separate analog ground plane.) How important these are to the average Arduino-like application is probably subject to debate.2) The circuitry you have on RESET seems overly complex and a bit wrong. the cap, which avr042 says is only needed for especially noisy environments and probably interferes with both AVR debugWire and Arduino auto-reset. The pullup resistor should be at least 10k, in order not to interfere with debugWire (so say AVR042!) (The diode is important, though, and not present in other tutorials afaik. It's lack can cause mysterious problems...

A couple of comments:1) re Ferrite bead on Vcca: AVR042 actually recommends the ferrite bead between the system power plane and digital Vcc, and the m328 datasheet recommends an actual inductor between Vcc and Vcca (as well as a separate analog ground plane.) How important these are to the average Arduino-like application is probably subject to debate.2) The circuitry you have on RESET seems overly complex and a bit wrong. the cap, which avr042 says is only needed for especially noisy environments and probably interferes with both AVR debugWire and Arduino auto-reset. The pullup resistor should be at least 10k, in order not to interfere with debugWire (so say AVR042!) (The diode is important, though, and not present in other tutorials afaik. It's lack can cause mysterious problems with auto-reset.)3) It'd be nice if this included an actual schematic as well as the fritzing diagrams, perhaps with the irrelevant pins removed.

No, you can have polygons even on a single sided board.There's an example in this instructable, and another here: https://www.instructables.com/id/Single-Sided-Reall...You do have to watch out for the polygon being "broken apart" by the other traces more than in a multi-layer design.

I notice that single element "fog devices" are less than 1/12th the price of the 12-element foggers (indeed - at about $10 each, less than 1/5th the price of the 5-element foggers!) Do you have any idea if twelve of the single-element foggers would be similar in production capability with the 12 element version?